• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.33-45
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• 1993

The variation of instrumental profile for the different scan speed of PDS is estimated as FWHM of the assumed Gaussian Profile. The effects of scan speed and scan aperture of PDS on the objective prism spectrum analysis are investigated for 8 combinations of scan speed and scan aperture. Amomg them. D1 apture with 15 csu is found to be the most optimum choice for measuring KISO objective prism film. We suggest the preliminary test study of the scan speed and aperture for the optimum use of PDS for any massive scan of spectra. The optimum scan speed and aperture depends on the dispersion of spectrum as well as the type of phtographic emulsion.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.147-155
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• 2002

In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.178-184
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• 2004

In this paper, we designed an image processing system for the high speed line-scan camera which adopts the new memory model we proposed. As a resolution and a data rate of the line-scan camera are becoming higher, the faster image processing systems are needed. But many conventional systems are not sufficient to process the image data from the line-scan camera during a very short time. We designed the memory controller which eliminates the time for transferring image data from the line-scan camera to the main memory with high-speed SRAM and has a dual-port configuration therefore the DSP can access the main memory even though the memory controller are writing the image data. The memory controller is implemented by VHDL and Xilinx SPARTAN-IIE FPGA.

• ETRI Journal
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• v.38 no.3
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• pp.479-486
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• 2016

System-on-chip (SoC) designs have a number of flip-flops; the more flip-flops an SoC has, the longer the associated scan test application time will be. A scan shift operation accounts for a significant portion of a scan test application time. This paper presents physical-aware approaches for speeding up scan shift operations in SoCs. To improve the speed of a scan shift operation, we propose a layout-aware flip-flop insertion and scan shift operation-aware physical implementation procedure. The proposed combined method of insertion and procedure effectively improves the speed of a scan shift operation. Static timing analyses of state-of-the-art SoC designs show that the proposed approaches help increase the speeds of scan shift operations by up to 4.1 times that reached under a conventional method. The faster scan shift operation speeds help to shorten scan test application times, thus reducing test costs.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.56-60
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• 2009

Purpose: The various studies and efforts to develop program are in progress in the field of nuclear medicine for the purpose of reducing scan time. The Oncoflash is one of the programs used in whole body bone scan which allows to maintain the image quality while to reduce scan time. When Those applications are used in clinical setting, both the image quality and reduction of scan time should be considered, therefore, the purpose of this study was to determine the criteria for proper scan speed. Materials and Methods: The subjects of this study were the patients who underwent whole body bone scan at the departments of nuclear medicine in the Asan Medical Center located in Seoul from 1st to 10th, July, 2008. The whole body bone images obtained in the scan speed of 30cm/min were classified by the total counts into under 800 K, and over 800 K, 900 K, 1,000 K, 1,500 K, and 2,000 K. The image quality were assessed qualitatively and the percentages of those of 1,000K and under of total counts were calculated. The FWHM before and after applying the Oncoflash were analyzed using images obtained in $^{99m}Tc$ Flood and 4-Quadrant bar phantom in order to compare the resolution according to the amount of total counts by the application of the Oncoflash. Considering the counts of the whole body bone scan, the dosed 2~5 mCi were used. 152 patients underwent the measurement in which the counts of Patient Postioning Monitor (PPM) were measured with including head and the parts of chest which the starting point of whole body bone scan from 7th to 26th, August, 2008. The correlations with total counts obtained in the scan speed of 30cm/min among them were analyzed (The exclusion criteria were after over six hours of applying isotopes or low amount of doses). Results: The percentage of the whole body bone image which has the geometric average of total counts of under 1,000K among them obtained in the scan speed of 30cm/min were 17.6%(n=58) of 329 patients. The qualitative analysis of the image groups according to the whole body counts showed that the images of under 1,000K were assessed to have coarse particles and increased noises. The analysis on the FWHM of the images before and after applying the Oncoflash showed that, in the case of PPM counts of under 3.6 K, FWHM values after applying the Oncoflash were higher than that before applying the Oncoflash, whereas, in the case of that of over 3.6 K, the FWHM after applying the Oncoflash were not higher than that before applying the Oncoflash. The average of total counts at 2.5~3.0 K, 3.1~3.5 K, 3.6~4.0 k, 4.1~4.5 K, 4.6~5.0 K, 5.1~6.0 K, 6.1~7.0 K, and 7.1 K over (in PPM) were $965{\pm}173\;K$, $1084{\pm}154\;K$, $1242{\pm}186\;K$, $1359{\pm}170\;K$, $1405{\pm}184\;K$, $1640{\pm}376\;K$, $1,771{\pm}324\;K$, and $1,972{\pm}385\;K$, respectively and the correlations between the counts in PPM and the total counts of image obtained in the scan speed of 30 cm/min demonstrated strong correlation (r=.775, p<.01). Conclusions: In the case of PPM coefficient over 3.6 K, the image quality obtained in the scan speed of 30cm/min and after applying the Oncoflash was similar to that obtained in the scan speed of 15 cm/min. In the case of total counts over 1,000 K, it is expected to reduce scan time without any damage on the image quality. In the case of total counts under 1,000 K, however, the image quality were decreased even though the Oncoflash is applied, so it is recommended to perform the re-image in the scan speed of 15 cm/min.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.2
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• pp.74-78
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• 2006

This paper presents a high-speed pulse-based flip-flop with pseudo MUX-type scan compatible with the conventional master-slave flip-flop with MUX-type scan. The proposed flip-flop was implemented as the standard cell library using Samsung 130nm HS technology. The data-to-output delay and power-delay-product of the proposed flip-flop are reduced by up to 59% and 49%, respectively. By using this flop-flop, ARM11 softcore has achieved the maximum 1GHz operating speed.

• Smart Structures and Systems
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• v.22 no.2
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• pp.223-230
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• 2018

This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a $100{\times}100mm^2$ area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.2004-2009
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• 2007

A new high-speed drive method for the plasma display panel is proposed. In this method, the address period is inserted for the rest period of the sustain pulses and the priming pulse is applied on the entire panel at the same time overlapping with the sustain period. The ramp shaped priming pulse can be made with a simple drive circuit in this technology and the stable sustain discharge can be induced even by a narrow scan pulse in help of the space charge generated from the address discharge. From the experiments, it is ascertained that the priming pulse hardly influences the sustain discharge. Moreover, the voltage margin of the sustain discharge is almost constant though that of the address discharge broadens with narrowing the scan pulse width. And, if the time interval between the scan pulse and the sustain pulse is within $6{\mu}s$, the voltage margin of the address and the sustain discharges are unaffected though the applied position of the scan pulse is changed. High-speed driving with the address pulse of $0.7{\mu}s$ width was achieved and the address voltage margin of 20V and the sustain voltage margin of 10V were obtained.

• Journal of The Korean Astronomical Society
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• v.25 no.1
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• pp.23-46
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• 1992

The electrical, mechanical and optical capabilities have been tested of the microdensitometer PDS 1010GMS at the Korea Astronomy Observatory. The highest stage of scan speed 255 csu (conventional speed unit) is measured to be 47 mm/s. At this speed the position is displaced by $4{\mu}m$ to the direction of scanning and the density is underestimated by $0.4{\sim}0.7D$. Standard deviation in the measured density is proportional to $A^{-0.46}$, where A is the area of scan aperture. The accuracy of position repeatability is ${\pm}1{\mu}m$, and that of density repeatability is ${\pm}(0.003{\sim}0.03)D$. Callier coefficient is determined to be 1.37; the semispecular density is directly proportional to the diffuse density up to 3.5D. Because the logarithmic amplifier has a finite response time, the densities measured at high scan speeds are underestimated to the degree that speeds higher than 200 csu are inadequate for making an accurate astronomical photometry. After power is on, an about 5 hour period of warming is required to stabilize the system electrically and mechanically as well. On the basis of this performance test, we have determined the followings as the optimum scan parameters for the astronomical photometry: For the scan aperture $10\;\sim\;20{\mu}m$ is optimal, and for the scan speed. $20\;{\sim}\;50$ csu is appropriate. These parameter values are chosen in such a way that they may keep the density repeatability within ${\pm}0.01D$, the position displacement under $1{\mu}m$, and the density underestimation below 0.1D even in high density regions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.25-31
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• 2018

Selective Laser Melting is one of the representative 3D printing techniques for handling metal materials. The main factors influencing the characteristics of structures fabricated by the SLM method include the build-up angle of structures, laser power, laser scan speed, and scan spacing. In this study, the tensile properties of AlSi10Mg alloys were investigated by considering the build-up angle of tensile test specimens, laser scanning speed and scan spacing as variables. The yield stress, tensile strength, and elongation were considered as tensile properties. From the test results, it was confirmed that the yield stress values were lowered in the order of 0, 45, and 90 based on the manufacturing direction of the tensile specimen. The maximum yield stress value was obtained at 1870 mm / min based on the laser scan speed. The yield stress size decreased with decreasing scan speed. Based on the laser scan spacing, as the value increases, the yield stress increases, but the variation is smaller than the other test criteria. The tendency of the tensile strength and elongation variation depending on the test conditions was difficult to understand.